12 weeks of training, then 12 weeks of detraining: which adaptations stay, which disappear?

Take a moment to look at the graph below. It's a little busy, but there's some interesting stuff in there: This is from a new European Journal of Applied Physiology paper by researchers in Japan and at the University of Laval in Canada . They took six sedentary subjects and had them train an hour a day, five times a week at lactate threshold pace, for 12 weeks. Then they stopped training for 12 weeks. The researchers then analyzed the changes in gene expression in the subjects' muscles, first from 12 weeks of training, then from 12 weeks of de training. One thing that's obvious is that, after 12 weeks, most of the training adaptations have disappeared. External changes in traits like VO2max, body composition and muscle fiber type all returned to roughly their starting values. In the gene expression study, 77% of the transcripts that responded to training reverted to their ...